But Arnaud Deboeuf—senior vice president of Renault-Nissan BV, the company's strategic management unit—said recently that the Leaf and Zoe could soon share a platform, and compete in the same segment.

That would mean either shrinking the Leaf into a subcompact, or growing the Zoe.

A future Mitsubishi electric car would use this same shared platform, according to the Nikkei report.

Mitsubishi eX Concept, 2015 Tokyo Motor Show

One candidate for such a vehicle might be the production version of the Mitsubishi eX concept, an all-electric compact crossover utility vehicle the company has shown at auto shows for two years.

That car was originally expected to be in production soon, but it appears to have been delayed. If produced, it would likely share underpinnings with a future all-electric Nissan crossover about the size of the Rogue.

Mitsubishi now sells only the i-MiEV, an aging electrified version of a tiny Japanese "kei" car also sold as the Citroën C-Zero and Peugeot iOn in Europe.